Nowadays actuators, for example ceramic piezoelectric actuators, are employed by various systems (touchpads, inkjet, etc.). These ceramics must be placed individually onto the final system and require high actuation voltages (typically 100 to 200 V).
In parallel, the use of actuators deposited in thin layers by means of microelectronics methods allows numerous systems to be batch-produced by virtue of step sharing (one microelectronics step is carried out at the same time on all of the systems present on the substrate), and thus allows manufacturing costs to be decreased. Moreover, thin film actuators allow electromechanical systems to be actuated through the use of low voltages (typically 10 to 20 V). However, due to their low thickness and small dimensions, the deformation afforded by these actuators is less than that obtained when using piezoelectric ceramics, and they transmit less force or entrain less movement than ceramics.
One exemplary application relates to haptic interfaces. Currently, mobile telephone manufacturers that have entered the touchscreen cell phone market seek to distinguish themselves by integrating haptic interfaces with force feedback into their units. Thus, when a user slides his or her finger over an icon located on the screen, he or she may feel a slight vibration arising from the cell phone, which vibration is intended to convey the sensation of pressing a button. However, nowadays, haptic systems embedded, for example, in cell phones exhibit a limited haptic effect (simple vibration) and overly high power consumption.
Another exemplary application for which it is advantageous to amplify the deformation of an actuator is found in those fields in which it is sought to produce a variable capacitor or switch.
This problem is also encountered when it is sought to produce, for example, an MEMS loudspeaker using an actuator on a diaphragm. The actuation of the diaphragm allows an acoustic pulse to be produced.
This same problem is also relevant to the field of photoacoustic imaging. In this case the acoustic pulse, generated by the movement of air entrained by the actuation of the diaphragm, is delivered to a cell or an element to be “probed”. The reflection of the acoustic wave may be recorded and analyzed in order to produce images.
Other fields of application may also be mentioned, such as those of micropumps, where the movement of a diaphragm is used as a micropump for example in order to dispense insulin or any other drug.
Within this general context, it remains advantageous and necessary to be able to have small structures available in which an effect initiated by an actuator may be transmitted, while being amplified, to an element to which this actuator is coupled.